[syslog-ng] placing dollar sign into patterdb tag values

I would like to place a $ character into the value of a tag/vlue pair using the patternDB but I can't find a way to do it. It seems that everything I have tried the patternDB engine interprets the $ as the start ov a variable expansion. Does anyone know if this can be done? An then the follow up question "How?" Thanks for your time.